The present invention relates to an improvement in non-magnetic austenitic stainless steel.
Pinch rolls are used in continuous casting machine for continuously withdrawing a slab or the like from a mold containing molten steel. When the slab passes between the pinch rolls, the inner portion of the slab is still in a molten state and is prone to segregation in the course of solidification. Accordingly an electromagnetic stirrer is provided for at least one of pinch rolls to produce a moving magnetic field and pass the slab through the magnetic field, thereby causing lines of magnetic force to stir the unsolidified inner portion of the slab to improve the quality of the portion. Rolls for use in electromagnetic stirrer are preferable to be the lowest in magnetic permeability so as to minimize the eddy current loss by electro-magnetic induction and to enhance an efficiency of electro-magnetic stirring. The electro-magnetic stirrer rolls are also required to have high hardness in view of durability and further to have good weldability in view of maintenance works.
The materials heretofore used for such rolls include 0.03C--18Cr--8Ni steel (AISI 304). However, the steel is about 1.006 in magnetic permeability (.mu.) and about 165 in Vickers hardness (VHN) and is not fully satisfactory in magnetic permeability and hardness, so that it is required to develop non-magnetic alloys having a lower magnetic permeability, higher hardness and better weldability.